Lenovo IdeaPad 3 Series Hardware Maintenance Manual page 46

"Remove the lower case" on page 32
Step 1. Disconnect the cable from the system board.
Attention: Use your fingernail to pull the connector to unplug it. Do not pull the cable.
Figure 16. Disconnect the cable
Step 2. Remove six screws and then remove the battery pack.
Figure 17. Remove the battery pack
Screw specifications
M2 x L3.5
Go to
https://support.lenovo.com/partslookup
replacement part:
40
IdeaPad 3/IdeaPad 3i/IdeaPad Slim 3/IdeaPad Slim 3i series Hardware Maintenance Manual
Number of screws
6
to look up the Lenovo part numbers of the following